Compositions for metal surface reformation



nite States This invention relates generally to compositions to be used for the reformation of metallic or organic plastic surfaces presenting substantially contiguous, relatively sharp microscopic crests, points or ridges, and depressions or valleys, which may result from any of various formings, workings or machinings of the metal, and which may adversely affect the metal in rendering it susceptible to such conditions as gallin g by severed particles, fretting, failure at points of sharp discontinuity, excessive coefficient of fraction and wear rates, accelerated corrodability and impaired lubricant retentiveness.

The present material finds applicability for the surface conditioning of various ferrous and non-ferrous metals and their alloys, of which steels, aluminum, titanium, manganese, alloys of iron, nickel, chromium, beryllium, magnesium, carbide ceramets, and brass are illustrative. In. any instance, the condition requiring reformation of the metal is manifested by such surface contours as microscopically fine, sharp edge craters, machine tool ridging, burrs or semi-free particles, any of which are creative of one or more of the adverse properties mentioned above. In this connection, it may be observed that the surface condition to be overcome, or improved, may have resulted from blasting with sand or other abrasives that sharply pit and weaken the skin strength of the metal, and increase its susceptibilities to other undesirable influences or effects.

Our general object is to provide an improved slurry composition which may be used by a process involving essentially, selective cold working and displacement of the metal forming the irregularities, to give a final surface finish, the exactness of which is controllable as will later appear, all without distortion of thin sections and without significant alteration of the final tolerances of the workpiece. Of particular importance is the capacity of the material as used in the process to accomplish these results as applied to parts that may have become corroded, soiled or otherwise contaminated so that their true surface conditions, defects and probable weaknesses cannot be observed. Use of the present material makes possible not only corrective surface working of the metal, but assures also the opportunity for visual inspection of the treated surface in the true color of the metal, which affords the most favorable condition for detailed revelation of its physical condition, including the presence or absence of defects.

Intricate and thin metal shapes'can be worked to a surface condition which cannot be achieved by conventional shot peening practices and surface blasting materials, and using the present material it is possible to satisfactorily work surfaces which respond adversely to impact by conventionally blasted shot or abrasives. In result, the comparison is that in accordance with the invention, excessive displacement of the metal in the impact area is obviated, and single effects or combinations thereof are obtained without distortion of thin sections or deterioration of workpiece tolerances. Application of the present material results in rounding or curving all sharp irregularities to a matte finish which serves as an improved surface for lubricant retention and exhibits improved resistance to corrosion and wear. Mitigation of surface porosity is. obtainable for both base metals and ice particles of bead-like form, which when blasted against. the surface of the workpiece, give rounding peening to the initially relatively sharp microscopic protuberances but without abrading or penetrating the metal surface in the manner resulting from the usual shot or abrasive particle blasting or peenin g practices commonly employed for such purposes as to deliberately roughen and excessively deform or work harden the metal surface. Accomplishment of our objects is predicated upon the use of a certain kind of small bead particles characterized by their having elastic properties ideally suited to accomplishment of the desired surface reformation, and further by their having in a liquid carrier, impact energy sufficiently great for the described limited working of the metal and yet sufiiciently low as not to abrade or excessively displace or work harden the metal. We have achieved our objectives by the use of bead-like particles made ofrglass, which term is intended to included all glasses and vitreous or fused spherical silicious particles. Glass has elasticity and toughness or resistance to fracture in the very small particle sizes herein contemplated. Usable glasses include those employed in the making of road striping spheres. We particularly contemplate the use of spheres made from glass that is substantially lead-free and therefore resistance to fracture under high velocity impact. Such stronger or more fracture-resistant glasses obviously are desirable when the spheres are subjected to repeated impacting as in recycle of the slurry.

In addition to selection of glass as the bead material and blasting the spheres in a carrier liquid, accomplishment of our objectives requires limitation of the sphere sizes within the range of about 0.003 to 0.032 inch, the size range usable in the average instance being in the range of about 0.003 to 0.014 inch. In the surface conditioning of a workpiece having relatively coarse or large size irregularities, we may first blast the surface with a dispersion of beads predominately in the larger particle plated coatings, and residual stresses from machining or sizes of the 0.003 to 0.032 rauge, and then follow this initial treatment by one or more similar blasting with smaller or progressively smaller size particles, generally to conform the bead size in accordance with progressive reduction and shaping of the surface irregularities.

As to the liquid carrier, we preferably use a water base liquid because of greater economy, the desirable fluidity of water, the complete metal cleaning action of a compounded aqueous carrier, and the practicability of supplementing water with one or more materials promotive of uniform dispersion of the beads and protection to be given the metal surface against contamination, rusting or other forms of corrosion. In preparing the bead dis persion we use a ratio of about 40 to weight parts of beads in the stated size range to 100 weight parts of the total liquid, i.e. water together with any added non-aqueous liquid. As additive bead dispersing agents We may use any of various materials, particularly of a soluble and non-foaming, or non-ionic organic nature, known to be effective for dispersing finely divided solids in water without producing objectionable foaming. Of these, we prefer to use any of various non-ionics which have the property of forming inverted emulsions with water insoluble oils, typically light mineral oils in which the oil constitutes the disperse phase, so that the dis persant may be a prepared oil and water emulsion to he added to the solids and a greater amount of water. As illustrative organic dispersing agents we may use the alkyl polyethoxyl phenols such as Oronite Chemical Companys non-ionic dispersants sold as Oronite Ni-W, which is the .12 ethylene oxide adduct of dodecyl phenol, and Oronite Ni-O understood to be the 3 to 6 ethylene oxide adduct of dodecyl benzene. These may be used alone or together with a light oil such as kerosene, typically in the proportion of about 95% kerosene and of Oronite Ni-W (2 parts) and Oronite Ni-O" (1 part). An effective dispersant may consist of an emulsion of about 80% of the resulting mixture, with about 20% water. This emulsion may be added to a glass bead-water slurry, in an amount (less than 2% of the total materials usually being sufiicient) required for good head dispersion.

The non-ionic component may be selected from the general class of (l) the polyoxyalkylene ethers of alkyl phenols, and (2) polyoxyalkylene ethers of aliphatic alcohols, and (3) the polyoxyalkylene esters of aliphatic acids. Typical non-ionics in group (1) are Antara Products Companys Antarox A-400 which is a nonyl phenol condensed with 9 to 10 moles of ethylene oxide, Carbide and Carbon Chemical Companys Tergitol NPGlOl which is a similar ethylene oxide condensate of octyl and nonyl phenols, and General Dycstutfs l'gepal CA Extra which is a dodecyl phenol condensed with 12 moles of ethylene oxide. Typical of the second group are General Dyestutfs Emulfor ELA which i an ethylene oxide condensate of higher fatty acids including lauric acid, and E. F. Houghton & Companys Cerfax 1300 which is a polyethylene glycol ether obtained by condensing ethylene oxide with a higher fatty alcohol. The contemplated nonionics may further be designated as including the alkyl (octyl to tetradecyl) phenols which are condensed with 8 to 14 moles of ethylene oxide to form liquid nonionic ethers.

As illustrative of other dispersants, we may use a bentonite of the aqua gel (minus 300 mesh) grade preferably with a small percentage of wetting agent, such as those mentioned above. Also usable is sodium or potassium carboxy methyl cellulose (e.g. Du ,Pont grade ZWX-high viscosity) with a small percentage (under 1%) of non-ionic wetting agent.

Any of various known anti-corrosion or anti-rust agents may be used, the specific selection being uncritical. Typical, are mixtures of sodium benzoate and sodium nitrite, sodium dichromate and sodium nitrite, as illustrative of inorganic inhibitors, and such organic inhibitors as Union Carbides Amine 220, understood to be 1 hydroxyl ethyl 2-hepta decenyl glyoxalidine, and such amines as the dior mono-cyclohexylamines.

As will be understood, appropriate dispersing agents may be used in quantities within the range of about .02 to 2 weight percent of the total water and dispersing agent, and ordinarily a suitable rust-preventing or anticorroding material may be used in concentrations under one percent, e.g. from about .02 to 1 percent, of the total liquid. In some instances it may be desirable to increase appreciably the viscosity of the carrier liquid, for which purpose We may add thereto a water soluble alcohol or glycol Whose viscosity is greater than that of water, or we may add other viscosity increasing materials such as solubilized mineral or vegetable oils providing that the carrier liquid will leave the treated metal surface clean in the respect that the surface will display the true color of the metal. Whether for purposes of viscosity control or for promoting suspension in the liquid of the dispersed beads, the carrier liquid may be compounded as an emulsion of water with a nonaqueous viscosity increasing agent, such as so-called solubilized mineral or vegetable oils, of which about kerosene weight mineral oilis preferred and may be used in quantities of 'about'0.1 to 10% of the total carrier liquid.

As used, the bead slurry will e e agitated in a pressurized container from which the slurry is discharged through a spray device or gun against the Work surface as a high velocity blast, all as more fully described in our copending application Serial No. 743,661, filed June 23, 1958 on Reformation of Metallic Surfaces, and of which the present application is a continuation-impart.

The following are illustrative usable glass bead slurry formulations, in which the non-ionics Ni-W and Ni-O are the Oronite Chemical Company wetting agents referred to hereinabove, and for which other of the listed nonionics may be substituted, if desirable, those given below being illustrative, though preferred.

Example I Glass beads (0.0030.005 in. size) -lbs 50 Water s 70 NiW oz /2 Ni-O v 07 A Sodium nitrite -0z /2 Sodium dichromate oz /2 Example II Glass beads (0005-0010 in. size) lbs 50 Water lbs 95 Ni .W n7 /1, Ni-O pt /2 Kerosene n7 /2 Sodium nitrite oz /2 Sodium dichromate oz /2 Example Ill Glass beads (0.12-0.027 in.) lbs 50 Water lbs 100 Ni-W oz 1% Ni-O oz 2 Kerosene pt 1 Bentonite (aqua gel grade) 0z 3 Sodium benzoate .oZ /2 Sodium nitrite 0z 1 /2 In preparing kerosene-containing formulations such as are given in Examples H and III, it is generally preferred to form first an emulsion of the organic dispersing agent or agents and kerosene with a small percentage of the total water, and to add the emulsion thus formed to an agitated mixture of the water and glass beads. The anticorrosion agent or agents may initially be put into the preformed emulsion or the aqueous bead slurry. The following further example will illustrate the use .of such preformed emulsions.

Example IV Ni Wn n7 Ni-O n1 1% Kerosene qts .3 Water p 1 /2 Sodium nitrite oz Sodium dichromate ..oz /2 This mixture is agitated to form a milky emulsion in which'the water appears to constitute the dispersed phase. One quart of this emulsion is then added to:

Glass beads (0.003 to 0.027 in. range) lbs I '50 Water lbs 75 mixed with the dispersing agent, mineral oil and rust inhibitor, which may be furnished for ultimate use by the addition of water in the proportions described.

We claim:

1. A composition for use in blast peening of microscopically irregular surfaces, consisting essentially of solid substantially spherical glass beads in the size range of about 0.003 to 0.032 inch, admixed with a carrier liquid comprising an aqueous solution of an organic essentially non-foaming dispersing agent for promoting suspension of the beads, said composition being substantially free from solid non-spherical abrasive particles.

2. A composition for use in blast peening of microscopically irregular surfaces, consisting essentially of solid substantially spherical glass beads in the size range of about 0.003 to 0.032 inch, admixed with a carrier liquid comprising an aqueous solution of an organic essentially non-foaming dispersing agent for promoting suspension of the beads, and a water soluble corrosion inhibitor, said composition being substantially free from solid nonspherical abrasive particles.

3. A composition for use in blast peening of microscopically irregular surfaces, consisting essentially of solid substantially spherical glass beads in the size range of about 0.003 to 0.032 inch, admixed with a carrier liquid comprising an aqueous solution of an organic essentially non-foaming dispersing agent for promoting suspension of the beads, the quantity of said dispersing agent being between about .02 and 2.0 weight percent of the carrier liquid water, said composition being substantially free from solid non-spherical abrasive particles.

4. A composition for use in blast peening of microscopically irregular surfaces, consisting essentially of solid substantially spherical glass beads in the size range of about 0.003 to 0.032 inch, admixed with a carrier liquid comprising an aqueous solution of an organic essentially non-foaming dispersing agent for promoting suspension of the beads, and a water soluble corrosion inhibitor, the quantity of said dispersing agent being between about .02 and 2 weight percent of the carrier liquid water and the rust inhibitor being between about .02. to 1 weight percent of the carrier liquid water, said composition being substantially free from solid non-spherical abrasive particles.

5. A composition for-use in blast peening of microscopically irregular surfaces, consisting essentially of solid substantially spherical glass beads in the size range of about 0.003 to 0.032 inch, admixed with a carrier liquid comprising an aqueous solution of an organic essentially non-foaming dispersing agent for promoting suspension of the beads, said agent including an alkyl polyethoxyphenol, said composition being substantially free from solid nonspherical abrasive particles 6. A composition for use in blast peening of microscopically irregular surfaces, consisting essentially of solid substantially spherical glass beads in the size range of about 0.003 to 0.032 inch, admixed with a carrier liquid comprising an essentially non-foaming aqueous emulsion of light mineral oil and an organic dispersing agent for promoting suspension of the beads, said composition being substantially free from solid non-spherical abrasive particles.

7. A composition for use in blast peening of microscopically irregular surfaces, consisting essentially of solid substantially spherical glass beads in the size range of about 0.003 to 0.032 inch, admixed with a carrier liquid comprising an aqueous emulsion of light mineral oil and an organic essentially non-ionic dispersing agent for promoting suspension of the beads, and a water soluble corrosion inhibitor, said composition being substantially free from solid non-spherical abrasive particles.

8. A composition for use in blast peening of microscopically irregular surfaces, consisting essentially of solid substantially spherical glass beads in the size range of about 0.003 to 0.032 inch, admixed with a carrier liquid 0 comprising an aqueous solution of an organic essentially non-foaming dispersing agent for promoting suspension of the beads, the beads and carrier liquid being in the ratio of about 40 to pounds of the beads to 100 pounds of the carrier liquid, said composition being substantially free from solid non-spherical abrasive particles.

9. A composition for use in blast peening of microscopically irregular surfaces, consisting essentially of solid substantially spherical glass beads in the size range of about 0.003 to 0.032 inch, admixed with a carrier liquid comprising an aqueous solution of an onganic essentially non-foaming dispersing agent for promoting suspension of the beads, and a water soluble corrosion inhibitor, the quantity of said dispersing agent being between about .02 to 2 Weight percent of the carrier liquid water and the rust inhibitor being between about .02 to 1 weight percent of the carrier liquid water, the beads and carrier liquid being in the ratio of about 40 to 100 pounds of the beads to 100 pounds of the carrier liquid, said composition being substantially free from solid non-spherical abrasive particles.

10. A composition for use in blast peening of microscopically irregular surfaces, consisting essentially of solid substantially spherical glass beads in the size range of about 0.003 to 0.032 inch, admixed with a carrier liquid comprising an aqueous emulsion of light mineral oil and an organic essentially non-ionic dispersing agent for promoting suspension of the beads, the beads and carrier liquid being in the ratio of about 40 to 100 pounds of the beads to 100 pounds of the carrier liquid, said composition being substantially free from solid non-spherical abrasive particles.

11. A composition for use in blast peening of microscopically irregular surfaces, consisting essentially of solid substantially spherical glass beads in the size range of about 0.003 to 0.032 inch, admixed with a carrier liquid comprising an essentially non-foaming aqueous emulsion of light mineral oil and an organic dispersing agent for promoting suspension of the beads, said mineral oil constituting between about .1 to 10% of the carrier liquid,

said composition being substantially free from solid nonspherical abrasive particles.

12. The composition of claim 1 containing also bentonite.

13 A packaged composition for use in blast peening of microscopically irregular surfaces, consisting essentially of solid substantially spherical glass beads in the size range of about 0.003 to 0.032 inch, admixed with a carnot liquid comprising a mineral oil, and an essentially non-foaming dispersing agent for promoting suspension of the beads, said composition being substantially free from solid non-spherical abrasive particles, said mineral oil beng emulsifiable with water in the presence of said dispersmg agent.

14. A packaged composition for use in blast peening of microscopically irregular surfaces, consisting essentially of solid substantially spherical glass beads in the size range of about 0.003 to 0.032 inch, admixed with a carrier liquid comprising a mineral oil, a rust inhibitor, and an essentially non-foaming dispersing agent for promoting suspension of the beads, said composition being substantlally free from solid non-spherical abrasive particles, said mineral oil being emulsifiable with water in the presence of said dispersing agent.

References Cited in the file of this patent UNITED STATES PATENTS Kullenberg Mar. 24, 1959 

1. A COMPOSITION FOR USE IN BLAST PEENING OF MICROSCRPICALLY IRREGULAR SURFACES, CONSISTING ESSENTIALLY OF SOLID SUBSTANTIALLY SPHERICAL GLASS BEADS IN THE SIZE RANGE OF ABOUT 0.003 TO 0.032 INCN, ADMIXING WITH A CARRIER LIQUID COMPRISING AN AQUEOUS SOLUTION OF AN ORGANIC ESSENTIALLY NON-FOAMING DISPERSING AGENT FOR PROMOTING SUSPENSION OF THE BEADS, SAID COMPOSITION BEING SUBSTANTIALLY FREE FROM SOLID NON-SPHERICAL ABRASIVE PARTICLES. 